/*****************************************************************************/
/*                                                                           */
/*                                loadexpr.c                                 */
/*                                                                           */
/*               Load an expression into the primary register                */
/*                                                                           */
/*                                                                           */
/*                                                                           */
/* (C) 2004-2009, Ullrich von Bassewitz                                      */
/*                Roemerstrasse 52                                           */
/*                D-70794 Filderstadt                                        */
/* EMail:         uz@cc65.org                                                */
/*                                                                           */
/*                                                                           */
/* This software is provided 'as-is', without any expressed or implied       */
/* warranty.  In no event will the authors be held liable for any damages    */
/* arising from the use of this software.                                    */
/*                                                                           */
/* Permission is granted to anyone to use this software for any purpose,     */
/* including commercial applications, and to alter it and redistribute it    */
/* freely, subject to the following restrictions:                            */
/*                                                                           */
/* 1. The origin of this software must not be misrepresented; you must not   */
/*    claim that you wrote the original software. If you use this software   */
/*    in a product, an acknowledgment in the product documentation would be  */
/*    appreciated but is not required.                                       */
/* 2. Altered source versions must be plainly marked as such, and must not   */
/*    be misrepresented as being the original software.                      */
/* 3. This notice may not be removed or altered from any source              */
/*    distribution.                                                          */
/*                                                                           */
/*****************************************************************************/

/* cc65 */
#include "codegen.h"
#include "error.h"
#include "exprdesc.h"
#include "global.h"
#include "loadexpr.h"

/*****************************************************************************/
/*                                   Code                                    */
/*****************************************************************************/

static void LoadConstant(unsigned Flags, ExprDesc *Expr)
/* Load the primary register with some constant value. */
{
  switch (ED_GetLoc(Expr)) {

  case E_LOC_ABS:
    /* Number constant */
    g_getimmed(Flags | TypeOf(Expr->Type) | CF_CONST, Expr->IVal, 0);
    break;

  case E_LOC_GLOBAL:
    /* Global symbol, load address */
    g_getimmed((Flags | CF_EXTERNAL) & ~CF_CONST, Expr->Name, Expr->IVal);
    break;

  case E_LOC_STATIC:
  case E_LOC_LITERAL:
    /* Static symbol or literal, load address */
    g_getimmed((Flags | CF_STATIC) & ~CF_CONST, Expr->Name, Expr->IVal);
    break;

  case E_LOC_REGISTER:
    /* Register variable. Taking the address is usually not
    ** allowed.
    */
    if (IS_Get(&AllowRegVarAddr) == 0) {
      Error("Cannot take the address of a register variable");
    }
    g_getimmed((Flags | CF_REGVAR) & ~CF_CONST, Expr->Name, Expr->IVal);
    break;

  case E_LOC_STACK:
    g_leasp(Expr->IVal);
    break;

  default:
    Internal("Unknown constant type: %04X", Expr->Flags);
  }
}

void LoadExpr(unsigned Flags, struct ExprDesc *Expr)
/* Load an expression into the primary register if it is not already there. */
{
  if (ED_IsLVal(Expr)) {

    /* Dereferenced lvalue. If this is a bit field its type is unsigned.
    ** But if the field is completely contained in the lower byte, we will
    ** throw away the high byte anyway and may therefore load just the
    ** low byte.
    */
    if (ED_IsBitField(Expr)) {
      Flags |= (Expr->BitOffs + Expr->BitWidth <= CHAR_BITS) ? CF_CHAR : CF_INT;
      Flags |= CF_UNSIGNED;
    } else {
      Flags |= TypeOf(Expr->Type);
    }
    if (ED_NeedsTest(Expr)) {
      Flags |= CF_TEST;
    }

    switch (ED_GetLoc(Expr)) {

    case E_LOC_ABS:
      /* Absolute: numeric address or const */
      g_getstatic(Flags | CF_ABSOLUTE, Expr->IVal, 0);
      break;

    case E_LOC_GLOBAL:
      /* Global variable */
      g_getstatic(Flags | CF_EXTERNAL, Expr->Name, Expr->IVal);
      break;

    case E_LOC_STATIC:
    case E_LOC_LITERAL:
      /* Static variable or literal in the literal pool */
      g_getstatic(Flags | CF_STATIC, Expr->Name, Expr->IVal);
      break;

    case E_LOC_REGISTER:
      /* Register variable */
      g_getstatic(Flags | CF_REGVAR, Expr->Name, Expr->IVal);
      break;

    case E_LOC_STACK:
      /* Value on the stack */
      g_getlocal(Flags, Expr->IVal);
      break;

    case E_LOC_PRIMARY:
      /* The primary register - just test if necessary */
      if (Flags & CF_TEST) {
        g_test(Flags);
      }
      break;

    case E_LOC_EXPR:
      /* Reference to address in primary with offset in Expr */
      g_getind(Flags, Expr->IVal);
      break;

    default:
      Internal("Invalid location in LoadExpr: 0x%04X", ED_GetLoc(Expr));
    }

    /* Handle bit fields. The actual type may have been casted or
    ** converted, so be sure to always use unsigned ints for the
    ** operations.
    */
    if (ED_IsBitField(Expr)) {
      unsigned F = CF_INT | CF_UNSIGNED | CF_CONST | (Flags & CF_TEST);
      /* Shift right by the bit offset */
      g_asr(F, Expr->BitOffs);
      /* And by the width if the field doesn't end on an int boundary */
      if (Expr->BitOffs + Expr->BitWidth != CHAR_BITS && Expr->BitOffs + Expr->BitWidth != INT_BITS) {
        g_and(F, (0x0001U << Expr->BitWidth) - 1U);
      }
    }

    /* Expression was tested */
    ED_TestDone(Expr);

  } else {
    /* An rvalue */
    if (ED_IsLocExpr(Expr)) {
      if (Expr->IVal != 0) {
        /* We have an expression in the primary plus a constant
        ** offset. Adjust the value in the primary accordingly.
        */
        Flags |= TypeOf(Expr->Type);
        g_inc(Flags | CF_CONST, Expr->IVal);
      }
    } else {
      /* Constant of some sort, load it into the primary */
      LoadConstant(Flags, Expr);
    }

    /* Are we testing this value? */
    if (ED_NeedsTest(Expr)) {
      /* Yes, force a test */
      Flags |= TypeOf(Expr->Type);
      g_test(Flags);
      ED_TestDone(Expr);
    }
  }
}
